The proposed research is concerned with the molecular basis of morphogenesis in vertebrate embryos and tumors. A functional assay for retino-tectal recognition in vitro is being pursued as a biochemical assay. This approach has shown that the ganglioside GM2 is involved in adhesion between retinal and tectal cells. Current studies are aimed at the elucidation of other molecules as well as at finding the receptor for the GM2 in this system. Other work involves the characterization of cell surface glycosyltransferases on gastrulating chick embryos and the role of such enzymes in the widespread morphogenesis that occurs in these embryos at these times. Initial experiments show that specific interference with appropriate enzymes can cause predictable teratogenesis in the area of the caudal spinal column and the eyes. These data are being actively pursued. Other subjects of study are mouse neurological mutations, mouse fertilization and cell interactions between malignant and non-malignant, cultured fibroblasts. BIBLIOGRAPHIC REFERENCES: Marchase, R.B., Meunier, J.-C., Pierce, M. and S. Roth. 1977. Biochemical investigations of retino-tectal specificity. J. Supramolec. Struct., in press. Durr, R., Shur, B., and S. Roth. 1977. Sperm-associated sialyltransferase activity. Nature 265,547-548.